U.S. patent number 6,977,053 [Application Number 10/246,488] was granted by the patent office on 2005-12-20 for manufacturing method of front-end component of endoscope.
This patent grant is currently assigned to Fujinon Corporation. Invention is credited to Hiroaki Fujita, Katsunori Mukasa.
United States Patent |
6,977,053 |
Mukasa , et al. |
December 20, 2005 |
Manufacturing method of front-end component of endoscope
Abstract
The invention relates to a method of manufacturing a front-end
optical component of an endoscope realizing resistance to humidity.
In the method of manufacturing a front-end optical component in
which a lens is mounted on the front end of a metallic lens-barrel
provided on the front end of the inserting portion of an endoscope,
the configuration is made such that a lens raw material is placed
on the front-end side in the lens-barrel, the lens raw material is
press-formed in a heat-softened state with a pair of upper and
lower shaping dies, thereby tightly joining the outer edge of the
pressed lens raw material to the inner peripheral surface of the
lens-barrel.
Inventors: |
Mukasa; Katsunori (Saitama,
JP), Fujita; Hiroaki (Saitama, JP) |
Assignee: |
Fujinon Corporation (Saitama,
JP)
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Family
ID: |
19118558 |
Appl.
No.: |
10/246,488 |
Filed: |
September 17, 2002 |
Foreign Application Priority Data
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Sep 27, 2001 [JP] |
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2001-297485 |
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Current U.S.
Class: |
264/1.7; 264/2.7;
65/39; 65/59.4 |
Current CPC
Class: |
A61B
1/00096 (20130101); A61B 1/00101 (20130101); C03C
27/02 (20130101) |
Current International
Class: |
B29D 011/00 () |
Field of
Search: |
;264/1.1,1.7,1.33,2.7
;65/39,59.1,59.4 ;425/808 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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10-29825 |
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Feb 1998 |
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JP |
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10-170794 |
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Jun 1998 |
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JP |
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10-234652 |
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Sep 1998 |
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JP |
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Primary Examiner: Vargot; Mathieu D.
Attorney, Agent or Firm: Jordan and Hamburg LLP
Claims
What is claimed is:
1. A method of manufacturing a front-end optical component in which
a lens is mounted on the front end of a metallic lens-barrel
provided on the front end of the inserting portion of an endoscope,
comprising the steps of: placing a lens raw material on the
front-end side in the lens-barrel, press-forming the lens raw
material in a heat-softened state with a pair of upper and lower
shaping dies, tightly joining the outer edge of the pressed lens
raw material to the inner peripheral surface of the lens-barrel;
and wherein the front end of the lens-barrel is placed so as to
straddle an outer periphery of a transfer surface shaped on a top
surface of the lower die of said pair of upper and lower shaping
dies, a guide die is provided so as to enclose the periphery of the
lens-barrel, the upper die has a transfer surface shaped on a
bottom surface thereof and is provided in the lens-barrel so as to
able to be inserted in and withdrawn from it, a portion of the lens
raw material press-formed by the upper and lower dies is formed
projecting toward the front-end side of the lens-barrel from its
inside, and the projection-shaped portion is polished and
finished.
2. The method of manufacturing a front-end optical component of an
endoscope according to claim 1, wherein a coefficient of linear
thermal expansion of a metallic material configuring said
lens-barrel is selected to be equal to or more than the coefficient
of linear thermal expansion of the lens raw material such that the
lens-barrel can fasten the lens raw material in a cooling process
after heat pressurizing.
3. The method of manufacturing a front-end optical component of an
endoscope according to claim 1, wherein the coefficient of linear
thermal expansion of a metallic material configuring the
lens-barrel is 100 to 170, and the coefficient of linear thermal
expansion of the lens raw material is 70 to 160.
4. The method of manufacturing a front-end optical component of an
endoscope according to claim 3 wherein a difference between the
coefficients of linear thermal expansion of the lens-barrel and the
lens raw material is not more than 100 at most.
5. The method of manufacturing a front-end optical component of an
endoscope according to claim 2, wherein the coefficient of linear
thermal expansion of a metallic material configuring the
lens-barrel is 100 to 170, and the coefficient of linear thermal
expansion of the lens raw material is 70 to 160.
6. The method of manufacturing a front-end optical component of an
endoscope according to claim 5 wherein a difference between the
coefficients of linear thermal expansion of the lens-barrel and the
lens raw material is not more than 100 at most.
7. A method of manufacturing a front-end optical component in which
a lens is mounted on the front end of a metallic lens-barrel
provided on the front end of the inserting portion of an endoscope,
comprising the steps of: placing a lens raw material on a front-end
side in a lens-barrel, press-forming lens raw material in a
heat-softened state with a pair of upper and lower shaping dies,
and tightly joining the outer edge of the pressed lens raw material
to an inner peripheral surface of the lens-barrel; and wherein a
guide die is mounted on the lower die having a transfer surface
shaped on a top surface thereof, a step portion is shaped on an
inner peripheral surface of the guide die, a flange portion shaped
on an outer peripheral surface of the lens-barrel is engaged with
the step such that the lens-barrel may be supported by the guide
die, thereby shaping space between the front end of the lens-barrel
and the lower die, the lens raw material is placed on the transfer
surface of the lower die, the upper die having a transfer surface
shaped on the bottom surface thereof is inserted into the
lens-barrel to press-form the lens raw material, a portion of the
press-formed lens raw material is formed projecting toward the
front-end side of the lens barrel from its inside so as to cover
the front end of the lens-barrel, and the projection-shaped portion
is polished and finished except for the covered front end portion
of the lens-barrel.
8. The method of manufacturing a front-end optical component of an
endo scope according to claim 7, wherein a coefficient of linear
thermal expansion of a metallic material configuring said
lens-barrel is selected to be equal to or more than a coefficient
of linear thermal expansion of the lens raw material such that the
lens-barrel can fasten the lens raw material in a cooling process
after heat pressurizing.
9. The method of manufacturing a front-end optical component of an
endoscope according to claim 7 wherein a coefficient of linear
thermal expansion of a metallic material configuring the
lens-barrel is 100 to 170, and a coefficient of linear thermal
expansion of the lens raw material is 70 to 160.
10. The method of manufacturing a front-end optical component of an
endoscope according to claim 9, wherein a difference between the
coefficients of linear thermal expansion of the lens-barrel and the
lens raw material is not more than 100 at most.
11. The method of manufacturing a front-end optical component of an
endoscope according to claim 8 wherein the coefficient of linear
thermal expansion of a metallic material configuring the
lens-barrel is 100 to 170, and the coefficient of linear thermal
expansion of the lens raw material is 70 to 160.
12. The method of manufacturing a front-end optical component of an
endoscope according to claim 11 wherein a difference between the
coefficients of linear thermal expansion of the lens-barrel and the
lens raw material is not more than 100 at most.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method of manufacturing a front-end
optical component in which a lens is mounted on the front end of
the lens-barrel provided at the front-end of the inserting portion
of an endoscope.
2. Description of the Related Art
Although a front-end optical component configuring the inserting
portion of an endoscope has a lens mounted at the front end of the
lens-barrel, the lens is bonded and fixed to the inside surface of
the lens-barrel with a epoxy-based adhesive. For example, in the
front-end optical components of the endoscopes disclosed in the
gazettes of Japanese Patent Laid-Open No. 10-234652 and Japanese
Patent Laid-Open No. 10-170794, both of the lens are fixed to the
lens-barrels with adhesives.
The main body of the front-end portion in the inserting portion of
an endoscope is provided with observing means having an objective
optical system positioned in the proximity of illuminating means.
The objective optical system is usually configured by a plurality
of lenses, and these lenses are mounted in a lens-barrel. Herein, a
first lens located on the nearest side to a body to be observed of
the lens-barrel is a planoconcave lens, of which concave surface is
adapted to be located within the lens-barrel. For example, during
testing, a pollution substance, such as a body fluid, can adhere to
the surface of the first lens exposed to the outside at the front
end of the inserting portion, and the adherence of the pollution
substance may impair the visual field of observation. Therefore,
the inserting portion is provided with a lens surface-cleaning
mechanism for washing out pollution substances from the surface of
the first lens. The lens surface-cleaning mechanism is provided
with a nozzle for issuing a jet of cleaning fluid toward the
outside surface of the first lens, and issues a jet of cleaning
fluid, usually washing water, from this nozzle to wash out
pollution substances. Then, the mechanism blows pressurized air on
the lens surface to remove washing water remaining on the lens
surface. Further, when existing in a body cavity, the first lens is
in a state of about the same temperature as the body temperature.
In the case of an electronic endoscope, the first lens can be in a
state of a higher temperature than the body temperature due to the
existence of a heating element, such as a solid image sensor. On
the other hand, the washing water is not particularly heated up,
and therefore the temperature of the washing water is held about at
the same temperature as the room temperature. For this reason, when
the washing water is jetted on the outside surface of the first
lens, the first lens can be quickly cooled. As a result of cooling
the first lens, if moisture is contained in the air in the
lens-barrel, fogging or condensation can be caused on the inside
surface side of the first lens. Moreover, because the inside
surface of the first lens is configured by a concavely curved
surface and its curvature is large, the temperature decrease is
most remarkable at the central portion thinnest in thickness and
its neighborhood in the first lens, thus resulting in fogging or
condensation concentrated on the central portion in the concave
surface of the first lens. Since light beams necessary for image
formation is concentrated in the central portion of the concave
surface of the first lens, least fogging of this region would cause
rapid decrease in the image quality of observational images
obtained, thereby resulting in a very difficult-to-look image.
Further, in some other cases, when the front end of the inserting
portion is also quickly cooled, there is also a fear that fogging
or condensation may take place on the first lens and the like.
In this manner, since fogging or condensation can possibly take
place on the lens (first lens) of the front-end optical component
of an endoscope, as a measure for preventing this, no
moisture-containing gas such as dry air and nitrogen gas has been
filled in the space in the lens-barrel.
In the first place, taking in moisture into the lens-barrel is
caused by that the first lens is bonded to the lens-barrel with an
adhesive and moisture can pass through this adhesive. The adhesive
is pervious to water in nature, and therefore moisture enters into
the lens-barrel through an adhesive layer between the first lens
and the lens-barrel, resulting in fogging of the first lens.
SUMMARY OF THE INVENTION
Therefore, the invention has an object to provide a method of
manufacturing a front-end optical component able to prevent the
entry of moisture into a lens-barrel, in which a lens is fixed,
without using an adhesive, on the front-end side of a lens-barrel
configuring the front-end optical component of an endoscope.
In order to achieves the above object, in a method of manufacturing
a front-end optical component in which a lens is mounted on the
front end of a metallic lens-barrel provided on the front end of
the inserting portion of an endoscope, the invention configures the
front-end optical component in such a manner that a lens raw
material is placed on the front-end side in the lens-barrel, the
lens raw material is press-formed in a heat-softened state with a
pair of upper and lower shaping dies, thereby tightly joining the
outer edge of the pressed lens raw material to the inner peripheral
surface of the lens-barrel.
According to the invention, a lens raw material is placed on the
front-end side in the lens-barrel, the lens raw material is
press-formed in a heat-softened state with a pair of upper and
lower shaping dies, thereby tightly joining the outer edge of the
pressed lens raw material to the inner peripheral surface of the
lens-barrel, and further, the coefficient of linear thermal
expansion of a metallic material configuring the lens-barrel is
selected to be equal to or more than the coefficient of linear
thermal expansion of the lens raw material such that the
lens-barrel can fasten the lens raw material in a cooling process
after heat pressurizing. Thereby, the lens raw material and the
front end side of the lens-barrel can be joined to each other into
one piece without using of an adhesive as in a conventional method.
Because of no use of an adhesive, there is no fear of the intrusion
of humidity into the lens barrel through the adhesive layer.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross sectional view for showing a manufacturing
process for a front-end optical component according to the
invention;
FIG. 2 shows a cross sectional view in press forming;
FIG. 3 is a cross sectional view for showing the state of the lens
raw material joined to the lens-barrel, which is taken out from the
shaping die;
FIG. 4 shows across sectional view of a front-end optical component
obtained by polishing the lens raw material;
FIG. 5 shows a cross sectional view of a shaping die in press
forming, showing another embodiment;
FIG. 6 is a cross sectional view of an entity taking out from the
shaping die as shown in FIG. 5; and
FIG. 7 is a cross sectional view for showing a front-end optical
component obtained by polishing the lens raw material.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1, a transfer surface 10A is shape on the top surface of a
lower die 10, a transfer surface 11A is shaped on the bottom
surface of a upper die 11, and a lens raw material 1 is adapted to
be press-formed by a pair of the upper and lower shaping dies 10
and 11. A guide die 12 is mounted on the lower die 10, and the
barrel die 12 and the lower die 10 together supports a metallic
lens-barrel 2. The upper die 11 is adapted to be inserted into the
lens-barrel 2. Further, the lens raw material 1 is placed on the
transfer surface 10A of the lower die 10, and positioned on the
front-end side of the lens-barrel 2. The front end of the
lens-barrel 2 is placed on the lower die 10 to straddle the outer
periphery of the transfer surface 10A.
FIG. 2 is a cross sectional view for showing a state in which the
upper die 11 is inserted into the lens-barrel 2 to press the lens
raw material 1 in cooperation with the lower die 10. Herein, the
outer edge of the pressed lens raw material 1 is tightly joined to
the inner peripheral surface of the front-end side of the
lens-barrel 2.
After the lens raw material 1 is properly cooled down in the
pressed state shown in FIG. 2, the shaping dies is opened and then
the lens barrel 2 and the lens raw material 1 are taken out. FIG. 3
shows an entity taken out at this time. In FIG. 3, a portion of the
lens raw material 1 pressed between the upper and lower dies 10 and
11 is shaped projecting toward the front-end side of the lens
barrel 2 from its inside, and this projection-shaped portion is
polished and finished into a plane (see FIG. 4). FIG. 4 is a cross
sectional view for showing the state of a completed front-end
optical component of an endoscope, and the lens raw material 1 is
configured into a lens 1A. The lens 1A is a planoconcave lens.
Stainless steel is preferable as a metallic material used for the
lens-barrel 2. The stainless steel used in the embodiment was
selected to have a coefficient of linear thermal expansion of
125.times.10.sup.-7 (1.degree. C.) and the coefficient of linear
thermal expansion of the lens raw material 1 was selected to be
124.times.10.sup.-7 (1.degree. C.). Preferably, the material of the
lens-barrel 2 has a coefficient of linear thermal expansion equal
to or more than that of the lens raw material 1. In a cooling
process subsequent to heat pressurizing of the lens raw material 1,
in order that the lens-barrel 2 expanded by heating and thereafter
shrinking by cooling can fasten the lens raw material, the
coefficient of linear thermal expansion of a metallic material
configuring the lens-barrel 2 should be equal to or more than that
of the lens raw material. SUS 430, SUS 430 F, SUS 444, and SUS 444F
or the like can be suitably used as the stainless steel. The
coefficients of linear thermal expansion of these stainless steel
materials are in the order of 100 to 170.times.10.sup.-7. When a
general optical glass is used as the lens raw material 1, its
coefficient of linear thermal expansion is in the order of 70 to
120.times.10.sup.-7. In the case of using SFS 01 of a lead
oxide-based glass among optical glass materials, its coefficient of
linear thermal expansion is 100.times.10.sup.-7. The coefficient of
linear thermal expansion of the lens raw material 1 used in the
embodiment, SFLD 21 (made in Sumita Optical Glass Corporation) is
124.times.10.sup.-7. A difference between the coefficients of
linear thermal expansion of the lens-barrel 2 and the lens raw
material 1 is desirably not less than 0 and not more than 100. If
the difference is larger this value, there is a fear that the
lens-barrel may too strongly fasten the lens during cooling.
FIG. 5 is a cross sectional view of a shaping die for showing
another embodiment. Herein, a guide die 12 is mounted on a lower
die 10 having a transfer surface 10A shaped on the top surface
thereof, a step portion 12A is shaped on the inner peripheral
surface of this barrel die 12. A flange portion 2A shaped on the
outer peripheral surface of the lens-barrel 2 is engaged with the
step portion 12A such that the lens-barrel 2 may be supported by
the barrel die 12, thereby providing a space between the front end
of the lens-barrel 2 and the lower die 10. The lens raw material 1
is placed on the transfer surface 10A of the lower die 10, and then
a upper die 11 having a transfer surface 11A shaped on the bottom
surface thereof is inserted into the lens-barrel 2, thereby
press-forming the lens raw material 1. Then, a portion of the
press-formed lens material 1 is adapted to be shaped projecting
toward the front-end side of the lens-barrel 2 from its inside so
as to cover the front end of the lens-barrel 2. FIG. 6 shows an
entity taken out from the shaping dies after cooling the lens raw
material. In FIG. 6, the front-end surface of the lens-barrel 2 is
covered with the lens raw material 1. This lens raw material is
polished and finished in a plane in the same manner as described
previously (see FIG. 7). As shown in FIG. 7, the outside periphery
side of the lens 1A covers the front end of the lens-barrel 2. This
is because an electric current-passing tool may be included in
treatment tools sent out from a treatment tool-inserting channel of
the inserting portion adjacent to the front-end optical component
of an endoscope, and such a tool may make contact with the front
end of the metallic lens-barrel 2, thus having an adverse effect on
the front-end optical component by energizing it. Thus, the front
end of the lens-barrel 2 is covered with the outer edge of the lens
1A, and thus the treatment tool makes contact with the outer edge
of the lens 1A covering the front end of the lens-barrel 2 but it
does not touch on the lens-barrel 2, thus eliminating a fear of
energization of the lens-barrel 2.
* * * * *